Flutter: Increment & decrement operators

The increment ++ and decrement -- operators increase or decrease the value of the operand by one.

There are two ways we can use them:

• Prefix: The operand value is incremented by one, then the new value is returned.
• Postfix: The original value of the operand is returned, then the operand is incremented by 1.

Postfix

When we use the operator as a postfix, we have to add it at the right side of the operand, for example:

int num = 5;
print( num++ ); // prints 5
print( num );   // prints 6

In the previous code fragment, the line print( num++) will print five because the original value of num is returned and printed and then increased by one.

Prefix

When we use the operator as a prefix, we have to add it at the left side of the operand, for example:

int num = 5;
print( ++num ); // prints 6
print( num );   // prints 6

This time, the value of num will be increased by one and then returned. That is why both print will print six.

Example in DartPad

Let's run some examples in DartPad: